Alphonsus and Arzachel
Point your telescopeat tonight’s first quarter Moon.Along the terminator,the shadow line between night and day,you might find these two large cratersstaring back at you withan owlish gaze.Alphonsus(left) andArzachelare ancient impact craters onthe north eastern shores of Mare Nubium, the lunar Sea of Clouds.The larger Alphonsus is over 100 kilometers in diameter.
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